CN105610133B

CN105610133B - Zone selective interlocking and circuit protection device monitoring in power distribution systems

Info

Publication number: CN105610133B
Application number: CN201510776619.6A
Authority: CN
Inventors: J.J.多赫蒂; M.E.瓦尔德斯
Original assignee: ABB Schweiz AG
Current assignee: ABB AS Norway
Priority date: 2014-11-14
Filing date: 2015-11-13
Publication date: 2019-12-06
Anticipated expiration: 2035-11-13
Also published as: CN105610133A; US20160141861A1; DE102015119603A1; US9564751B2

Abstract

Circuit protection devices, power distribution systems, and circuit protection device monitoring in Zone Selective Interlock (ZSI) systems are described. In one example, a circuit protection device for use with a ZSI power distribution system includes a trip mechanism configured to interrupt current flow through the circuit protection device and a trip unit operatively coupled to the trip mechanism. The trip unit is configured to monitor a current flowing through the circuit protection device, output a first signal when the monitored current is less than a threshold, and output a second signal when the monitored current is greater than or equal to the threshold. The first and second signals are different from each other and from no signal.

Description

Zone selective interlocking and circuit protection device monitoring in power distribution systems

background

The present application relates generally to power distribution systems and more particularly relates to zone selective interlocking and circuit protection device monitoring in power distribution systems.

known power distribution systems include a plurality of switchgear trains including circuit breakers each coupled to one or more loads. Circuit breakers typically include a trip unit that controls the circuit breaker based on a sensed current flowing through the circuit breaker. More specifically, if the current flowing through the circuit breaker is outside of acceptable conditions, the trip unit causes the current to be interrupted.

some known circuit breakers are programmed with one or more current thresholds (also referred to as "pick up" thresholds) that identify undesirable current levels for the circuit breaker. If the fault draws current in excess of one or more current thresholds for a predetermined amount of time, for example, the trip unit typically activates an associated circuit breaker to prevent current flow through the circuit breaker. However, in power distribution systems that include multiple circuit breakers, typical arrangements use a hierarchy of circuit breakers. Large circuit breakers (i.e. circuit breakers with a high current rating) are placed closer to the power supply than lower current feeder circuit breakers and supply lower current feeder circuit breakers. Each feeder circuit breaker may feed a plurality of other circuit breakers connected to loads or other distribution equipment.

A fault may occur anywhere in the breaker hierarchy. When a fault occurs, each circuit breaker with the same fault current flowing through it may detect a different amount of fault current due to varying sensor sensitivity and/or tolerances. When a fault occurs, the circuit breaker closest to the fault should operate to prevent current flow through the circuit breaker. If a circuit breaker higher in the hierarchy trips, multiple circuits or loads may unnecessarily lose service.

to accommodate varying tolerances and to ensure that multiple circuit breakers do not unnecessarily trip based on the same fault current, the current thresholds of at least some known circuit breakers are nested within each other to avoid overlapping fault current thresholds. In some other known systems, upon detection of a fault current, a circuit breaker in a lower tier sends a coordination or lockout signal to a higher tier circuit breaker. In response to the lockout signal, operation of the upper level circuit breaker is coordinated with operation of the lower level circuit breaker. In at least some known systems, the higher layer circuit breakers are unable to distinguish between a communication fault (e.g., a broken connection/disconnection) and a no-latch signal between the lower layer circuit breaker and the higher layer circuit breaker. When a communication fault occurs in such a system, the higher tier circuit breakers will still not realize that the lower tier circuit breakers have detected the fault and unnecessary nuisance tripping of the higher tier circuit breakers is more likely.

disclosure of Invention

in one aspect, a Zone Selective Interlocked (ZSI) power distribution system includes a first circuit protection device configured to interrupt current flow through the first circuit protection device, a second circuit protection device downstream of the first circuit protection device, and a controller. The second circuit protection device includes a trip mechanism configured to interrupt current flow through the second circuit protection device and a trip unit operatively coupled to the trip mechanism. The trip unit is configured to monitor a current flowing through the second circuit protection device, output a first signal when the monitored current is less than a threshold, and output a second signal when the monitored current is greater than or equal to the threshold. The first and second signals are different from each other and from no signal. The controller is configured to control the first circuit protection device in a first mode in response to the first signal, in a second mode in response to the second signal, and in a third mode in response to no signal from the second circuit protection device.

in another aspect, a circuit protection device for use with a ZSI power distribution system includes a trip mechanism configured to interrupt current flow through the circuit protection device and a trip unit operatively coupled to the trip mechanism. The trip unit is configured to monitor a current flowing through the circuit protection device, output a first signal when the monitored current is less than a threshold, and output a second signal when the monitored current is greater than or equal to the threshold. The first and second signals are different from each other and from no signal.

In yet another aspect, a controller for use with a ZSI power distribution system includes an output configured to be communicatively coupled to a first circuit protection device, an input configured to be communicatively coupled to a second circuit protection device downstream from the first circuit protection device, a memory device, and a processor coupled to the memory device. The controller is programmed to control the first circuit protection device in a first mode in response to detecting a first signal at the input, in a second mode in response to detecting a second signal at the input, and in a third mode in response to failing to detect the first signal or the second signal at the input for a determined period of time.

Another aspect is a ZSI power distribution system including a first circuit protection device configured to interrupt current flow through the first circuit protection device, a second circuit protection device downstream of the first circuit protection device, and a controller communicatively coupled to the second circuit protection device. The second circuit protection device includes a trip mechanism configured to interrupt current flow through the second circuit protection device and a trip unit operatively coupled to the trip mechanism. The trip unit is configured to monitor a current flowing through the second circuit protection device and output a first signal when the monitored current is less than a ZSI lockout threshold. The controller is configured to control the first circuit protection device in an unconstrained mode of operation in response to detecting the first signal and to control the first circuit protection device in a constrained mode of operation in response to failing to detect the first signal.

provides the technical proposal 1:

A Zone Selective Interlocking (ZSI) power distribution system, comprising:

a first circuit protection device configured to interrupt current flow through the first circuit protection device;

A second circuit protection device downstream of the first circuit protection device, the second circuit protection device comprising:

A trip mechanism configured to interrupt current flow through the second circuit protection device; and

A trip unit for operative coupling to the trip mechanism, the trip unit configured to:

Monitoring a current flowing through the second circuit protection device;

outputting a first signal when the monitored current is less than a threshold, an

outputting a second signal when the monitored current is greater than or equal to the threshold, wherein the first and second signals are different from each other and different from no signal; and

a controller configured to:

Controlling the first circuit protection device in a first mode in response to the first signal;

controlling the first circuit protection device in a second mode in response to the second signal; and

Controlling the first circuit protection device in a third mode in response to the absence of a signal from the second circuit protection device.

Provides the technical proposal 2: the ZSI power distribution system of claim 1, wherein the controller is disposed within the first circuit protection device.

Provides the technical proposal 3: the ZSI power distribution system of claim 1, wherein the first mode is an unconstrained mode of operation and the second mode is a constrained mode of operation.

provides the technical proposal 4: the ZSI power distribution system of claim 3, wherein the third mode is selectable between the constrained mode of operation and the unconstrained mode of operation.

Provides the technical proposal 5: the ZSI power distribution system of claim 4, wherein the controller is further configured to provide an alert in response to an absence of a signal from the second circuit protection device.

Provides the technical proposal 6: the ZSI power distribution system of claim 1, wherein the threshold is a ZSI lockout threshold that is less than a trip threshold of the second circuit protection device.

Provides the technical proposal 7: the ZSI power distribution system of claim 1, wherein the controller is configured to determine that there is no signal from the second circuit protection device when a determined period of time elapses without receiving at least one of the first signal and the second signal.

provides the technical proposal 8: the ZSI power distribution system according to claim 1, further comprising:

a third circuit protection device downstream of the first circuit protection device, the third circuit protection device configured to output the first signal when the monitored current through the third circuit protection device is less than the threshold and to output the second signal when the monitored current through the third circuit protection device is greater than or equal to the threshold; and

An aggregator communicatively coupled to the first, second, and third circuit protection devices, the aggregator configured to receive the first and second signals from the second and third circuit protection devices and to provide an aggregated output to the controller.

provides the technical proposal 9: the ZSI power distribution system of claim 8, wherein the aggregator is configured to provide an output indicating whether the first signal, the second signal, or no aggregation of the first and second signals has been detected.

Provides the technical proposal 10: the ZSI power distribution system of claim 9, wherein the aggregator is configured to:

Outputting the first signal to the controller when the first signal is received from both the first circuit protection device and a second circuit protection device;

Outputting the second signal to the controller when the second signal is received from any one of the first and second circuit protection devices;

Outputting the third signal to the controller when the first and second signals are not received from one of the first and second circuit protection devices and the second signal is not received from the other of the first and second circuit protection devices.

provides the technical proposal 11:

A circuit protection device for use with a Zone Selective Interlock (ZSI) power distribution system, the circuit protection device comprising:

a trip mechanism configured to interrupt current flow through the circuit protection device; and

monitoring a current flowing through the circuit protection device;

Outputting a first signal when the monitored current is less than a threshold; and is

Outputting a second signal when the monitored current is greater than or equal to the threshold, wherein the first and second signals are different from each other and different from no signal.

Provides the technical proposal 12: the circuit protection device of claim 11, wherein the threshold is a ZSI lockout threshold that is less than a trip threshold of the circuit protection device.

provides the technical proposal 13: the circuit protection device of claim 11 wherein the first signal comprises a discontinuous signal that repeats at substantially constant intervals when the monitored current is less than the threshold.

Technical solution 14 is provided: the circuit protection device of claim 13 wherein the intermittent signal has a duration less than the substantially constant interval.

Provides the technical proposal 15: the circuit protection device of claim 11 wherein the first signal has substantially the same magnitude as the second signal and the first signal has a different duration than the second signal.

Provides the technical proposal 16:

A controller for use with a Zone Selective Interlocking (ZSI) power distribution system, the controller comprising:

An output configured to be communicatively coupled to a first circuit protection device;

An input configured to communicatively couple to a second circuit protection device downstream of the first circuit protection device;

A storage device; and

A processor coupled to the storage device, the controller programmed to:

Controlling the first circuit protection device in a first mode in response to detecting a first signal at the input;

Controlling the first circuit protection device in a second mode in response to detecting a second signal at the input; and

controlling the first circuit protection device in a third mode in response to failing to detect the first signal or the second signal at the input for a determined period of time.

Provides the technical proposal 17: the controller of claim 16, wherein the first mode is an unconstrained mode of operation and the second mode is a constrained mode of operation.

Provides the technical proposal 18: the controller of claim 17, wherein the third mode is selectable between the constrained mode of operation and the unconstrained mode of operation.

Provides the technical proposal 19: the controller of claim 16, wherein the controller is further configured to provide an alert in response to failing to detect the first signal or the second signal at the input within the determined period of time.

Provides the technical proposal 20:

A Zone Selective Interlocking (ZSI) power distribution system, comprising:

monitoring a current flowing through the second circuit protection device;

Outputting a first signal when the monitored current is less than the ZSI latching threshold; and

a controller communicatively coupled to the second circuit protection device, the controller configured to:

controlling the first circuit protection device in an unconstrained mode of operation in response to detecting the first signal; and

controlling the first circuit protection device in a constrained mode of operation in response to failing to detect the first signal.

Drawings

FIG. 1 is a schematic block diagram of an exemplary power distribution system.

fig. 2 is a graphical representation of example continuous and discontinuous signals.

FIG. 3 is a schematic block diagram of another exemplary power distribution system.

fig. 4 is an illustration of an example aggregator that may be used in the system shown in fig. 3.

Fig. 5 is a schematic block diagram of an exemplary power distribution system including a communication bus.

Detailed Description

exemplary embodiments of circuit protection devices, Zone Selective Interlock (ZSI) power distribution systems, and methods of monitoring circuit protection devices and/or power distribution systems are described herein. An example system monitors the health of one or more communication channels between circuit protection devices in a ZSI system. The system is operable to detect when communications have failed, generate alarms, and/or operate higher level circuit protection devices accordingly. Further, the example system provides selective ZSI to allow the ZSI scheme to be configured to increase reliability and responsiveness or to reduce nuisance tripping of higher layer circuit protection devices.

fig. 1 is a schematic block diagram of a portion of an exemplary power distribution system 100 including a source 102 that provides power to a load 104 via a circuit protection device 106. The electrical power source 102 may include, for example, one or more generators or other devices that provide electrical current (and thus electrical power) to the load 104. Current is delivered to load 104 through distribution bus 108. The load 104 may include, but is not limited to, including only machines, motors, lighting, and/or other electrical and mechanical equipment of a manufacturing or power generation or distribution facility. Power distribution system 100 is a low voltage power distribution system rated to operate at Alternating Current (AC) voltages up to about 1 kilovolt (kV). In other embodiments, power distribution system 100 is a medium voltage system rated to operate at an AC voltage between about 1kv and about 52 kv. Alternatively, system 100 is rated to operate at any suitable voltage or voltage range.

in the illustrated embodiment, the circuit protection devices 106 are arranged in a hierarchy including a first layer 110 and a second layer 112 to provide different levels of protection and monitoring to the power distribution system 100. For example, a first circuit protection device 114 (sometimes referred to as a source circuit protection device) is disposed in the first layer 110 to receive current from the first source of electrical power 102 and provide current to the bus 108. A second circuit protection device 116 (sometimes referred to as a feeder circuit protection device) is disposed in the second layer 112 downstream of the first circuit protection device 114 and is connected to receive current from the bus 108. The second circuit protection device 116 provides current to the load 104. As used herein, the term "downstream" refers to a direction from the electrical power source 102 toward the load 104. The term "upstream" refers to a direction opposite to the downstream direction, e.g., from the load 104 toward the source of electrical power 102. Although fig. 1 illustrates the circuit protection devices 106 arranged in two layers 110 and 112, it should be appreciated that any suitable number of circuit protection devices 106 may be arranged in any suitable number of layers to enable the power distribution system 100 to function as described herein. For example, it should be appreciated that one or more additional layers and/or circuit protection devices 106 may be disposed between the electrical power source 102 and the first layer 110 in some embodiments. Additionally or alternatively, in some embodiments, one or more additional layers and/or circuit protection devices 106 may be disposed between the load 104 and the second layer 112. Further, one or more additional circuit protection devices 106 may be arranged to provide power (from any suitable source 102) to the bus 108. Similarly, one or more additional circuit protection devices may be connected to the bus 108 to provide power to one or more additional loads 104.

In the exemplary embodiment, circuit protection device 106 is a circuit breaker. Alternatively, the circuit protection device 106 may be any other device that enables the power distribution system 100 to function as described herein. In the exemplary embodiment, each circuit protection device 106 is an integrated trip unit that includes a controller configured to control the operation of circuit protection device 106. Alternatively, one or more of the circuit protection devices 106 may be non-integrated circuit protection devices 106 having separate components and/or one or more controllers. The circuit protection device 106 includes a trip unit 118 operatively coupled to a sensor 120 and a trip mechanism 122. The trip unit 118 is a controller configured to control the operation of the circuit protection device 106. In the exemplary embodiment, trip unit 118 is an Electronic Trip Unit (ETU) that includes a processor 124 coupled to a memory 126, an input device 128, and a display device 130. The trip unit 118 may include or be considered a computing device. In other embodiments, trip unit 118 may be any other suitable type of trip unit. In some embodiments, one or more of the circuit protection devices 106 include a different type of trip unit 118 and/or a different type of circuit protection device as compared to at least one other of the circuit protection devices 106. In some embodiments, the circuit protection device 106 does not include the trip unit 118, and the functions described herein as being performed by the trip unit 118 are instead performed by a central controller (not shown).

In the exemplary embodiment, sensor 120 is a current sensor that measures a current flowing through trip mechanism 122 and/or circuit protection device 106, such as a current transformer, Rogowski coil, hall effect sensor, and/or shunt. Alternatively, sensors 120 may include any other sensors that enable power distribution system 100 to function as described herein. Further, the sensor 120 may be integrated into the circuit protection device 106 or may be separate from the associated circuit protection device 106. Different sensors 120 may be used for different portions of the system 100. For example, the sensors 120 in the first layer 110 may be different from the sensors 120 in the second layer 112. Each sensor 120 generates a signal representative of a measured or detected current (hereinafter referred to as a "current signal") flowing through the associated trip mechanism 122 and/or circuit protection device 106. In addition, each sensor 120 transmits a current signal to a processor 124 associated with the trip mechanism 122 or coupled to the trip mechanism 122. Each processor 124 is programmed to activate the trip mechanism 122 to interrupt the current provided to the load 104 or the power distribution line or bus 108 if the current signal and/or the current represented by the current signal exceeds the current threshold.

The circuit protection devices 106 are communicatively coupled to each other. More specifically, the circuit protection device 106 is communicatively coupled to at least one upstream circuit protection device. In an example embodiment, the circuit protection devices 106 are communicatively coupled together via communication ports in their respective trip units 118. Each trip unit 118 includes an output port 132 (also referred to as an output) and an input port 134 (also referred to as an input) configured to transmit signals to and receive signals from other trip units 118. The ports 132 and 134 of each trip unit may be physically separate ports or may be a single physical port providing one or more virtual ports (e.g., ports 132 and 134). Ports 132 or 134 of trip unit 118 are coupled to ports 134 or 132 of another trip unit 118 by one or more wires 136. Although a single conductor 136 is shown connecting the output port 132 of the second circuit protection device 114 to the input port 134 of the first circuit protection device 114, any suitable number of conductors 136 may be used to couple the ports 132 and 136. Further, in some embodiments, ports 134 and 136 communicate using a wireless communication protocol without using any wires 136. In some embodiments, ports 132 and/or 134 are bidirectional (e.g., input/output) ports.

in the exemplary embodiment, trip mechanism 122 is a circuit breaker. An electrical signal is provided to the trip mechanism 122 to trip the circuit breaker and interrupt the flow of current through the trip mechanism 122. In other embodiments, the trip mechanism 122 includes, for example, one or more other circuit breaker devices and/or arc suppression devices. Exemplary circuit breaker devices include, for example, circuit switches, contact arms, and/or circuit interrupters that interrupt current flowing through the circuit breaker device to a load 104 coupled to the circuit breaker device. Exemplary arc suppression devices include, for example, a suppression assembly, a plurality of electrodes, a plasma gun, and a trigger circuit that causes the plasma gun to emit an ablative plasma into a gap between the electrodes to divert energy from an arc or other electrical fault detected on the circuit into the suppression assembly.

Each processor 124 controls operation of the circuit protection device 106 and collects measured operating condition data, such as data representative of current measurements (also referred to herein as "current data"), from sensors 120 associated with trip mechanisms 122 coupled to the processor 124. The processor 124 stores the current data in a memory 126 coupled to the processor 124. It should be appreciated that the term "processor" refers generally to any programmable system including systems and microcontrollers, Reduced Instruction Set Circuits (RISC), Application Specific Integrated Circuits (ASIC), programmable logic circuits, and any other circuit or processor capable of executing the functions described herein. The above examples are exemplary only, and are thus not intended to limit in any way the definition and/or meaning of the term "processor".

The memory 126 stores program code and instructions executable by the processor 124 to control the circuit protection device 106. The memory 126 may include, but is not limited to only including, non-volatile RAM (NVRAM), Magnetic RAM (MRAM), ferroelectric RAM (FeRAM), read-only memory (ROM), flash memory, and/or electrically erasable programmable read-only memory (EEPROM). Any other suitable magnetic, optical, and/or semiconductor memory, alone or in combination with other forms of memory, may be included in memory 126. The memory 126 may also be or include removable or removable memory including, but not limited to, suitable magnetic cassettes, magnetic disks, CD ROMs, DVDs, or USB memory.

Input device 128 receives input from, for example, a user, another trip unit 118, a remote computing device, etc. The input device 128 may include, for example, a keyboard, a card reader (e.g., a smart card reader), a pointing device, a mouse, a stylus, a touch sensitive panel (e.g., a touchpad or a touch screen), a gyroscope, an accelerometer, a position detector, a keypad, a communication port, one or more keys, and/or an audio input interface. A single component, such as a touch screen, may function as both the display device 130 and the input device 128. In some embodiments, input device 128 may include a communication interface to receive input from a remote computing device (including from another trip unit 118). Although a single input device 128 is shown, the trip unit 118 may include more than one input device 128 or no input devices 128.

The display device 130 visually presents information about the circuit protection device 106 and/or the trip mechanism 122. Display device 144 may include Vacuum Fluorescent Displays (VFDs), one or more Light Emitting Diodes (LEDs), Liquid Crystal Displays (LCDs), Cathode Ray Tubes (CRTs), plasma displays, and/or any suitable visual output device capable of visually conveying information to a user. For example, the processor 124 may activate one or more components of the display device 130 to indicate that the circuit protection device 106 and/or the trip mechanism 122 are active and/or operating properly, receiving a lockout signal, transmitting a lockout signal, indicating that a fault or failure has occurred, and/or indicating any other status of the trip mechanism 122 and/or the circuit protection device 106. In some embodiments, the display device 130 presents a Graphical User Interface (GUI) to a user for interaction between the user and the circuit protection device 106. The GUI allows a user to, for example, control the circuit protection device 106, monitor the operation/status of the circuit protection device 106, test the operation of the circuit protection device 106, and/or modify operating parameters of the circuit protection device 106.

The example system 100 is a Zone Selective Interlock (ZSI) system. Generally, when the amount of current detected by the downstream circuit protection device 106 exceeds the lockout threshold, the downstream circuit protection device 106 outputs a lockout signal to the upstream circuit protection device 106 via the output port 132. The lockout threshold is typically less than the trip threshold at which the downstream circuit protection device 106 trips. In response to receiving the lockout signal, the upstream circuit protection device 106 may transition from the unrestricted mode of operation to the restricted mode of operation to prevent the upstream and downstream circuit protection devices 106 from operating with similar trip sequences. Additionally or alternatively, in response to receiving a lockout signal from the downstream circuit protection device 106, the upstream circuit protection device 106 may switch to operate at or use a higher trip threshold, such as switching from a protective threshold to a standby threshold.

In some embodiments, in the unrestricted mode of operation, an unrestricted trip sequence including a cumulative time value where the current exceeds the protective threshold until the unrestricted time threshold is reached may be performed. In the constrained mode of operation, a constrained trip sequence may be performed that includes an accumulated time value where the current exceeds the standby threshold until the constrained time threshold is reached. Trip unit 118 generates a trip signal if either the constrained time threshold or the unconstrained time threshold is reached. Alternatively, the unrestricted trip timing and the restricted trip timing may include any other action or response that enables trip unit 118 to function as described herein. It should be appreciated that the unrestricted trip timing causes the trip signal to be generated in a shorter period of time than the period of time in which the restricted trip timing causes the trip signal to be generated.

in an example embodiment, a downstream circuit protection device 106, such as the second circuit protection device 116, is configured to output a first signal when the monitored current through the second circuit protection device 106 is less than a threshold, such as the ZSI lockout threshold. In response to the first signal, the upstream first circuit protection device 114 knows that the second circuit protection device 116 is functioning and that no current exceeding the threshold is detected. In response, the trip unit 118 controls the operation of the first circuit protection device 114 in the first mode. In an example embodiment, the first mode is an unconstrained mode of operation in the ZSI scheme.

the first signal may be a substantially continuous signal, a discontinuous signal, or a data signal in accordance with any suitable communication protocol. As shown in fig. 2, a substantially continuous signal 200 continuously maintains a determined value 202 (e.g., positive 5 volts, negative 2 volts, ground, etc.). The intermittent signal 204 includes a signal portion 206 that repeats at a substantially constant interval/period 208 and includes a portion 210 that is free of signal. In the illustrated example, the signal portion 206 is a series of pulses 212. In other embodiments, the signal portion may be a single pulse, more or fewer pulses, or any other suitable signal portion that may be detected by the receiving circuit protection device 206. In an example embodiment, the circuit protection device 106 communicates using active low communication and the first signal is output from the second circuit protection device 116 by pulling the output port 132 down to ground.

Referring again to fig. 1, the downstream circuit protection device 106, e.g., the second circuit protection device 116, is configured to output a second signal different from the first signal when the monitored current through the second circuit protection device 106 is equal to or greater than the ZSI lockout threshold. In response to the second signal, the upstream first circuit protection device 114 considers that the second circuit protection device 116 has detected a current that exceeds the ZSI lockout threshold and is handling a potential fault. The first circuit protection device 114 then operates in a second mode (e.g., switches to a constrained mode of operation) as configured under the particular ZSI system being implemented.

In an embodiment, the second signal is the same as the no signal. The first circuit protection device 114 detects the second signal by failing to detect any signal (whether the first signal or any other signal) at its input port 134. In some embodiments, the first circuit protection device 114 detects no signal by failing to detect any signal on its input port 134 for a period of time. The period of time may be any suitable length of time, such as a period greater than the period of the intermittent first signal. In this example embodiment, a communication fault (e.g., a broken conductor 136, a faulty output port 132, etc.) between the second circuit protection device 116 and the first circuit protection device 114 is identified by the upstream first circuit protection device 114 as being the same as the second signal. Thus, a communication fault causes the first circuit protection device 114 to operate in its ZSI scheme in the same manner (e.g., in a constrained mode) that it would if the fault had been detected by the downstream second circuit protection device 116, thus reducing nuisance tripping when a communication fault occurs. In other embodiments, the first signal is the same as the no-signal and a communication fault between the second circuit protection device 116 and the first circuit protection device 114 is identified by the upstream first circuit protection device 114 as being the same as the first signal. Thus, a communication failure causes the first circuit protection device 114 to operate in accordance with its ZSI scheme in the same manner (e.g., in an unconstrained mode) that it would have operated if no failure were detected by the downstream second circuit protection device 116.

in other embodiments, the second signal is different from the no signal and different from the first signal. The second signal may be a substantially continuous signal, a discontinuous signal, or a data signal in accordance with any suitable communication protocol. In an example embodiment, one of the first signal and the second signal is a continuous signal and the other is a discontinuous signal. In other embodiments, the first signal and the second signal are different intermittent signals. In all such embodiments, the ZSI aspect of system 100 is a tri-state logic system. The signal received by the first circuit protection device 114 from the second circuit protection device 116 may be a first signal/state indicating that the second circuit protection device 116 has not detected current exceeding the ZSI lockout threshold, may be a second signal/state indicating that the second circuit protection device 116 has detected current exceeding the ZSI lockout threshold, and may be a third signal/state (i.e., no first or second signal) indicating a communication failure between the first and second circuit protection devices 114 and 116. In response to detecting the first signal, the trip unit 118 of the first circuit protection device controls the first circuit protection device 114 in a first mode (e.g., an unconstrained mode). In response to detecting the second signal, the first circuit protection device 114 is controlled by its trip unit 118 to be in a second mode (e.g., a constrained mode). When the third signal is detected (i.e., when neither the first signal nor the second signal is detected), the trip unit 118 controls the first circuit protection device 114 in the third mode. In some embodiments, the third mode is the same as one of the first mode or the second mode. In some embodiments, the third mode is selectable, for example by a user, between the first mode, the second mode, or a different mode. Therefore, the processing of the first circuit protection device for communication failure can be selectively configured arbitrarily for a specific system. For example, in a system where nuisance tripping is highly disruptive, the third mode may be configured to be the same as the second mode. Thus, if a communication fault occurs, the trip unit 118 will operate the first circuit protection device 114 in a constrained mode of operation of the second mode. Similarly, if nuisance tripping is not a concern or a higher level of protection is desired, the third mode may be configured to be the same as the first mode, allowing the first circuit protection device 114 to operate in the first mode without restriction.

in a tri-state embodiment, trip unit 118 may also be configured to generate an alert in response to detecting the third signal. The alert may be a human recognizable alert (e.g., an audible or visible alert) and/or a computer recognizable alert. The generated alert may be a local alert, such as an audible or visible alert generated at the location of the first circuit protection device 114 or on the first circuit protection device 114. Additionally or alternatively, the generated alert may be a remote alert, such as an audible or visible alert generated at a location remote from the first circuit protection device, an alert transmitted to a remote computing device, or the like.

FIG. 3 is a schematic block diagram of a portion of another exemplary power distribution system 300. Except as described herein, system 300 is identical to system 100 (shown in fig. 1) and common components are identified by the same reference numerals. For clarity, some details of the circuit protection device 106, such as the trip unit 118, the sensor 120, and the trip mechanism 122, are omitted from fig. 3.

In an example embodiment, the system 300 includes the first circuit protection device 114 in the first layer 110. The first circuit protection device 114 couples power from the source 102 to the bus 108. Three circuit protection devices 106 in the second layer 112 are coupled to the bus 108 to transfer power from the bus 108 to the load 104. Other embodiments may include more or fewer layers and/or more or fewer circuit protection devices 106 in one or more layers. The circuit protection devices 106 in the second layer 112 include a second circuit protection device 116, a third circuit protection device 302, and a fourth circuit protection device 304. The output port 132 of the second layer 112 of circuit protection devices is coupled to the input port 134 of the aggregator 306 via a conductor 136.

each of the second, third and fourth circuit protection devices 116, 302 and 304 outputs a first signal via the output port 132 when the current flowing through its trip unit (not shown in fig. 3) is less than the ZSI lockout threshold and a second signal when the measured current equals or exceeds the ZSI lockout threshold.

The output signals from the second, third and fourth circuit protection devices 116, 302 and 304 are coupled to an aggregator 306. The aggregator 306 receives signals from the second layer 112 of circuit protection devices and provides an aggregated output to the controller of the first circuit protection device 114 via its output port 132. More specifically, the aggregator 306 provides the aggregated output to the trip unit 118 (not shown in fig. 3) of the first circuit protection device 114. Fig. 4 is an example aggregator 306 capable of receiving an active low input from eight circuit protection devices 106 that may be used in the system 300.

Referring again to fig. 3, in the tri-state system described above, the aggregated output is one of the first signal, the second signal, or the third signal (i.e., no signal) depending on the combination of inputs received by the aggregator 306. If any input to the aggregator 306 from the second tier 112 circuit protection device 106 is a second signal (indicating that the detected current is greater than the ZSI lockout threshold), the aggregator 306 outputs the second signal to the first circuit protection device 114. If none of the inputs to the aggregator 306 are the second signal and all of the inputs are the first signal (indicating that all of the detected currents are below the ZSI lockout threshold), the aggregator 306 outputs the first signal to the first circuit protection device 114. If none of the inputs to the aggregator 306 are the second signal and any of the inputs are the third signal (i.e., no signal), the aggregator 306 outputs the third signal to the first circuit protection device 114. In response to the signal from the aggregator 306, the first circuit protection device 114 operates in the same manner as it responds to the output signal from the second circuit protection device in the example embodiment described above with respect to fig. 1. Further, because the aggregator 306 provides the same signal to the first circuit protection device 114, the first circuit protection device 114 may be the same as the first circuit protection device 114 in the system 100 and need not know that it is receiving a signal from the aggregator, rather than from the circuit protection device 106.

in the illustrated embodiment, the aggregator 306 has four input ports 134. Other embodiments include more or fewer input ports. In some implementations, not all of the aggregator's input ports 134 will be used or needed. Each port may be switched on or off by an electrical, mechanical, or electromechanical switch to indicate to the aggregator 306 that the port is unused. The illustrated embodiment includes an unused port 308. Since the unused port 308 is not connected to the circuit protection device 106, it will never receive a signal. To prevent the aggregator 306 from erroneously interpreting this no-signal as a third signal, the unused port 308 is disconnected.

fig. 5 is a schematic block diagram of a portion of another exemplary power distribution system 500. Except as described herein, system 500 is identical to systems 100 (shown in fig. 1) and 300 (shown in fig. 3) and common components are identified by the same reference numerals. For clarity, some details of the circuit protection device 106, such as the trip unit 118, the sensor 120, and the trip mechanism 122, are omitted from fig. 5.

in an example embodiment, the system 500 includes the first circuit protection device 114 in the first layer 110. The first circuit protection device 114 couples power from the source 102 to the bus 108. The second circuit protection device 116, the third circuit protection device 302, and the fourth circuit protection device 304 are located in the second layer 112 and are coupled to the bus 108 to transfer power from the bus 108 to the load 104. Other embodiments may include more or fewer layers and/or more or fewer circuit protection devices 106 in one or more layers. In this example embodiment, the port 132 is a bidirectional input/output (I/O) port. The I/O ports 132 are coupled to a communication bus 502. The communication bus 502 may be any suitable wired or wireless communication bus. The circuit protection devices 106 communicate with each other via the communication bus 502 using serial communication, parallel communication, and/or any suitable communication protocol.

each of the second, third and fourth circuit protection devices 116, 302 and 304 periodically transmits a first message (also referred to as a first signal) via port 132 when the current flowing through its trip unit (not shown in fig. 5) is less than the ZSI lockout threshold and transmits a second message (also referred to as a second signal) when the measured current equals or exceeds the ZSI lockout threshold. The second, third, or fourth circuit protection device 116, 302, or 304 does not output the first message or the second message to the communication bus 502 when it is experiencing a problem and may not function properly. No first or second message from the second, third, or fourth circuit protection device 116, 302, or 304 may be considered a third message (also referred to as a third signal). In other embodiments, the third message may be different than the no message. For example, each of the second, third, and fourth circuit protection devices 116, 302, and 304 may provide a third message conveying what issues, if any, it is experiencing.

in response to the communication messages from the second, third and fourth circuit protection devices 116, 302 and 304, the first circuit protection device 114 operates in the same manner as it responds to the first, second and third signals from the second circuit protection device 116 in the example embodiment described above with respect to fig. 1.

In the example embodiment shown in fig. 5, the circuit protection devices 106 communicate with each other directly over a communication bus 502. In other embodiments, additionally or alternatively, the circuit protection device 106 communicates with a central controller (not shown) over the communication bus 502. The central controller directly or indirectly controls operation of the circuit protection devices 106 based at least in part on communications received from the circuit protection devices 106. For example, when any of the circuit protection devices 116, 302, or 304 sends a second message to the central controller indicating that it is detecting a current equal to or greater than the ZSI lockout threshold, the central controller may indirectly control the first circuit protection device 114 by commanding the first circuit protection device 114 to operate in a second mode (e.g., a constrained mode). The central controller may directly control the circuit protection device 106 by performing some or all of the functions that would otherwise be performed by the trip unit 118 (not shown in fig. 5) in the circuit protection device.

Technical effects of the methods and systems described herein may include one or more of the following: (a) reducing nuisance tripping of the circuit protection device; (b) alerting a user of a faulty communication connection between the circuit protection devices; and (c) providing a system configurable to reduce nuisance tripping or increase responsiveness.

Exemplary embodiments of circuit protection devices, power distribution systems, and methods of monitoring power distribution systems and/or circuit protection devices are described above in detail. The systems and methods are not limited to the specific embodiments described herein, but rather, components of systems and/or operations of the methods may be utilized independently and separately from other components and/or operations described herein. Furthermore, the described components and/or operations may also be defined in, or used in combination with, other systems, methods, and/or apparatus, and are not limited to practice with only the power system as described herein.

the order of execution or performance of the operations in embodiments of the invention illustrated and described herein is not essential, unless otherwise specified. That is, the operations described may be performed in any order, unless otherwise specified, and embodiments of the invention may include additional or fewer operations than those disclosed herein. For example, it is contemplated that executing or performing a particular operation before, contemporaneously with, or after another operation is within the scope of aspects of the invention.

Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the invention, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.

this written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Parts list

100 power distribution system

102 source

104 load

106 circuit protection device

108 distribution bus

110 first layer

112 second layer

114 first circuit protection device (upstream)

116 second circuit protection device (downstream)

118 trip unit

120 sensor

122 trip mechanism

124 processor

126 memory

128 input device

130 display device

132 output port

134 input port

136 wire

200 continuous signal

202 determined value

204 discontinuous signal

206 signal part

208 intervals/periods

210 no signal part

212 pulse

300 system

302 third circuit protection device

304 fourth circuit protection device

306 aggregator

308 unused port

500 power distribution system

502 communication bus.

Claims

1. a zone selective interlocking power distribution system comprising:

monitoring a current flowing through the second circuit protection device;

A controller configured to:

2. The zone selective interlocking power distribution system of claim 1, wherein the controller is disposed within the first circuit protection device.

3. The regionally selectively interlocked power distribution system of claim 1, wherein the first mode is an unconstrained mode of operation and the second mode is a constrained mode of operation.

4. The regionally selectively interlocked power distribution system of claim 3, wherein the third mode is selectable between the constrained mode of operation and the unconstrained mode of operation.

5. The zone selective interlocking power distribution system of claim 4, wherein the controller is further configured to provide an alert in response to the absence of a signal from the second circuit protection device.

6. The zone selective interlocking power distribution system of claim 1, wherein the threshold is a zone selective interlocking lockout threshold that is less than a trip threshold of the second circuit protection device.

7. The zone selective interlocking power distribution system of claim 1, wherein the controller is configured to determine that there is no signal from the second circuit protection device when a determined period of time elapses without receiving at least one of the first signal and the second signal.

8. The zone selective interlocking power distribution system of claim 1, further comprising:

9. The zone selective interlocking power distribution system of claim 8, wherein the aggregator is configured to provide an output indicating whether the first signal, second signal, or no aggregation of first and second signals has been detected.

10. The zone selective interlocking power distribution system of claim 9, wherein the aggregator is configured to:

outputting a third signal to the controller when the first and second signals are not received from one of the first and second circuit protection devices and the second signal is not received from the other of the first and second circuit protection devices.

11. a circuit protection device for use with a zone selective interlocking power distribution system, the circuit protection device comprising:

monitoring a current flowing through the circuit protection device;

Outputting a second signal when the monitored current is greater than or equal to the threshold, wherein the first and second signals are different from each other and different from no signal,

Wherein the threshold is a zone selective interlock lockout threshold that is less than a trip threshold of the circuit protection device.

12. The circuit protection device of claim 11, wherein the first signal comprises a discontinuous signal that repeats at substantially constant intervals when the monitored current is less than the threshold.

13. the circuit protection device of claim 12 wherein the intermittent signal has a duration less than the substantially constant interval.

14. The circuit protection device of claim 11, wherein the first signal has substantially the same amplitude as the second signal and the first signal has a different duration than the second signal.

15. A controller for use with a zone selective interlocking power distribution system, the controller comprising:

A storage device; and

A processor coupled to the storage device, the controller programmed to:

16. The controller of claim 15, wherein the first mode is an unconstrained mode of operation and the second mode is a constrained mode of operation.

17. The controller of claim 16, wherein the third mode is selectable between the constrained mode of operation and the unconstrained mode of operation.

18. The controller of claim 15, wherein the controller is further configured to provide an alert in response to failing to detect the first signal or the second signal at the input within the determined period of time.

19. A zone selective interlocking power distribution system comprising:

Monitoring a current flowing through the second circuit protection device;

outputting a first signal when the monitored current is less than a zone selective interlock lockout threshold; and